In general, the formation of color photographic images is carried out by a method comprising developing the exposed silver halide grains using an aromatic primary amine compound as a developing agent and coupling the thus obtained oxidation product of the aromatic primary amine compound with color-forming couplers to give a yellow dye image, a magenta dye image and a cyan dye image.
The above method usually employs cyan couplers, magenta couplers and yellow couplers.
Although color photographic images obtained by using these couplers are usually preserved as records for a long time or may be exhibited, the white grounds of these dye images are not always stable to light, heat and moisture. While the color photographic images are long exposed to light, preserved under the circumstance of high temperature and high humidity, or held in albums for many years, the white grounds thereof are sometimes discolored to cause the deterioration of image quality (which is called stains hereinafter).
There may be considered many possible sources of the stains. For example, the following sources (1) and (2) are presumed.
(1) The couplers themselves decompose to make the white ground yellow (which is called Y stain). PA0 (2) The developing agent remaining in an emulsion film after development processing is gradually oxidized with oxygen in the air and so on to be reacted with couplers to form dyes and then cause the stains. In this case, the use of a magenta coupler brings about the magenta stain. The magenta has the high relative luminosity to man to cause the lowering of image quality exceedingly. PA0 (1) the color density is lowered by the addition of sulfinic acid compounds containing oil-soluble groups; and PA0 (2) the stable emulsions cannot easily be obtained since the solubility of sulfinic acid compounds in auxiliary solvents (low boiling-point solvents) such as ethyl acetate to be used in emulsion dispersion is low.
Particularly, pyrazoloazole type magenta couplers show the better sharpness than 5-pyrazolone type magenta couplers both in the shorter wavelength side and the longer wavelength side, and so the former is most preferable in respect of color reproduction but unfavorable to have such a defect that the magenta color stain due to the above-mentioned source (2) easily occurs.
Moreover, there is another difficult problem as to a developing bath. The developing bath is seldom newly prepared in every development processing. In practice, a developing solution is supplied again according to the amount used for development. However, the solution composition is not maintained by adding only water used in development.
Namely, the developing solution usually consists of a color developing agent, a stop solution, a bleaching solution, a fixing or blix solution and so on. The composition of the developing solution is changed by the decomposition of the developing agent in the long processing kept at a high treating temperature of 31.degree. C. to 43.degree. C., the oxidation of said agent by contact with air, the accumulation of substances eluted from photosensitive materials, the carrying over of the developing solution attached to photosensitive materials to the next bath, and so on to bring about what is called a running solution. So the shortage of some agents used must be supplied and substances not wanted must be removed from the bath to regenerate the solution. However, this is not satisfactory.
When photosensitive materials are developed in such a running solution, the components of the developing solution remain in the photosensitive materials to easily cause the above mentioned color stains in particular.
The conventionally known methods of preventing various stains include those of using alkylhydroquinones (e.g., U.S. Pat. Nos. 3,935,016 and 3,960,570), chroman, coumaran (e.g., U.S. Pat. No. 2,360,290), phenolic compounds (e.g., JP-A No. 51-9449), and sulfinic acid polymers (e.g., JP-A No. 56-151937). (The term "JP-A" as used herein means an "unexamined published Japanese patent application"). These compounds were recognized to have a little effect on the stains formed by processing, but showed substantially no effect on those caused by moisture and heat given after color developing processing. Also, JP-A No. 56-67842 discloses that photosensitive materials contain compounds obtained by the reaction of nitrogen-containing organic bases or quaternary-nitrogen atom-containing compounds with sulfinic acid, an object of which is to provide silver halide photosensitive materials which are stable and suitable for rapid processing by adding and mixing aromatic primary amine compounds as precursors and another object of which is to stabilize the photographic property of the photosensitive materials before development. The objects thereof are essentially different from those of the present invention as stated hereinafter.
On the other hand, JP-A No. 62-143048 discloses that sulfinic acid compounds containing oil-soluble groups are effective to the above-mentioned stains. It is certain that said sulfinic acid compounds are effective, but have the following problems: